Due to an increasing number of wireless devices and a growing demand for wireless services, wireless communication systems continue to expand. To meet the growing demand, and to increase interoperability and reduce costs, various sets of standards have been introduced for wireless communications. One such set of standards developed for wireless communication is the Institute of Electrical and Electronics Engineers, Inc. (IEEE) 802.16. IEEE 802.16 includes the family of standards developed by the IEEE 802.16 committee, establishing standards for broadband wireless access. In part, the IEEE 802.16 family of standards defines interoperability of broadband Wireless Metropolitan Area Networks (WirelessMAN). Generally speaking, WirelessMANs are large networks utilizing wireless infrastructure to form connections between subscriber stations. WiMAX, a term defined and promoted by The WiMAX Forum™, is commonly used to refer to WirelessMANs and wireless communication and communication networks that are based on the IEEE 802.16 standard. As used herein, the term “WiMAX” refers to any communication network, system, apparatus, device, method, etc. that utilizes or is based on the 802.16 family of standards.
Included in the 802.16 family of standards is the IEEE 802.16e standard, which relates to mobile WiMAX. An update to the IEEE 802.16e standard has been proposed, called IEEE 802.16m. The IEEE 802.16e standard, and the proposed IEEE 802.16m standard, propose grouping connections according to their Quality of Service types to create Power Saving Classes (PSC). Each type of PSC has a set of message exchange procedures for its definition/activation/deactivation. Moreover, IEEE 802.16e, and the proposed IEEE 802.16m, define a general set of parameters and rules that can be used to design different sleep and listening windows. IEEE 802.16e enumerates three kinds of PSCs:
Type I Power Saving Class (Type 1 PSC): Groups together BE (Best Effort service) and NRT-VR (Non-Real-Time Variable Rate service) connections. A fixed length listening window alternates with a sleep window, where each sleep window is twice the size of a previous sleep window, to some maximum duration sleep window size. If there is incoming data, the next sleep window will be the length of the first sleep window.
Type II Power Saving Class (Type 2 PSC): Groups together UGS (Unsolicited Grant service), ERT-VR (Extended Real-Time Variable Rate service), and RT-VR (Real-Time Variable Rate service) connections. A fixed length listening window alternates with a fixed length sleep window.
Type III Power Saving Class (Type 3 PSC): Groups together multicast connections and management connections. A single sleep window has a duration based on an expected time period before activity. The duration and separation of the expected time period of activity and the sleep window, i.e., the expected time period before activity, is set based on an expected arrival of a next portion of data or next expected ranging request.
In addition, IEEE 802.16e, and the proposed IEEE 802.16m, supports a device mode. A device mode provides energy savings on a mobile station when the traffic load is low. A device mode consists of alternating unavailability intervals and availability intervals. Generally, during the unavailability interval the device cuts off all contact with its serving base station and conserves its energy. During the availability interval, the device actively waits for traffic and/or sends packets out. The unavailability interval is defined in IEEE 802.16e, and the proposed IEEE 802.16m, as a time interval that does not overlap with any listening window of any active PSC. The availability interval is defined in IEEE 802.16e, and the proposed IEEE 802.16m, as a time interval that does not overlap with any unavailability interval.
IEEE 802.16e defines the relationship between unavailability intervals and availability intervals, but does not discuss how to manage those intervals to optimize the unavailability of the device. Further, the actual definitions of multiple power saving classes may involve significant complexity in achieving efficient power savings.
The disclosed embodiments are directed to overcoming one or more of the problems set forth above.